Internal and external combustion engines produce exhaust gases that may reach very high temperatures. These temperatures may be high enough to pose a safety hazard to any personnel present near the engine's exhaust outlet-to-atmosphere.
To correct this problem, some engine manufacturers use exhaust pipes of sufficient length to cool the exhaust gas before it enters the environment. Unfortunately, some exhaust temperatures are too high and require additional cooling solutions.
Today, many engines are equipped with catalytic converters and particulate filters in the exhaust system that may further increase the exhaust outlet-to-atmosphere temperatures. For example, particulate filters may be configured to collect unburned hydrocarbons—or soot—from the engine's exhaust. Periodically, the filter regenerates, which causes these collected hydrocarbons to undergo an exothermic reaction and burn. This exothermic reaction may result in a large release of thermal energy, thereby further increasing the exhaust-to-outlet temperature.
U.S. Pat. No. 3,875,745 to Franklin (“'745”) discloses a device utilizing the Coanda effect to introduce exhaust gas around a lip on one end of a venturi tube, causing the exhaust gas to flow in a high velocity film adherent to the inner surface of the tube. The laminar flow of '745 draws in a large volume flow of air through the center of the venturi, cooling 1000° F. exhaust gas down to almost ambient temperature in a distance of a few inches.
The device of '745, however, may not be suitable for many applications. For example, according to '745, “For effective operation, the gases must pass through catalytic converter at a temperature not lower than 1000° F.” Further, the device of '745 may result in a prohibitively high exhaust back-pressure, thereby detrimentally affecting the engine's Brake Specific Fuel Consumption. Even further, the device of '745 may be expensive to manufacture, making its cost prohibitively expensive.
The disclosed exhaust-gas cooling device is directed to overcoming one or more of the problems set forth above.